Apelin-13 inhibits large-conductance Ca2+-Activated Kchannels in cerebral artery smooth muscle cells via a PI3-Kinase dependent mechanism

Abstract

Apelin-13 causes vasoconstriction by acting directly on APJ receptors in vascular smooth muscle (VSM) cells; However, the ionic mechanisms underlying this action at the cellular level remain unclear. Large-conductance Ca 2+-activated K(BKCa) channels in VSM cells are critical regulators of membrane potential and vascular tone. In the present study, we examined the effect of apelin-13 on BKCa channel activity in VSM cells, freshly isolated from rat middle cerebral arteries. In whole-cell patch clamp mode, apelin-13 (0.001-1 μM) caused concentration-dependent inhibition of BKCa in VSM cells. Apelin-13 (0.1 μM) significantly decreased BKCa current density from 71.25±8.14 pA/pF to 44.52±7.10 pA/pF (n=14 cells, P.